The images from the SDSS project are organized into stripes.
These are long images, 24,000 pixels (2.5 degrees) wide, and typically
over 1 million pixels (120 degrees) long. The SDSS covers the northern
sky with overlapping stripes. Each stripe is merged from two
runs, taken on separate nights. The telescope can complete only
a single 8-hour run in any given night.

Each run consists of 6 camcols (camera columns); one camcol corresponds to
each array of CCD detectors of our camera. Each camcol takes images in
five colors, from the ultraviolet to the infrared.

We have created color images by taking the middle three bands and assigning
those to the blue, green and red channels of the screen. The 1 million
pixel long camcols are broken up into many fields. Each SDSS field
is 2048 pixels wide by 1489 pixels high. The fields overlap along the scan direction
by 128 pixels. The fields can be uniquely named by the run number, the camcol
and the field number. The images of the fields can be downloaded by clicking on
Fields at the sidebar.

The SDSS project uses the color images to detect millions of objects
(over 300 million stars and galaxies) over the whole northern sky.
As soon as these objects are observed, a sophisticated software algorithm
selects targets for further studies. Using another instrument, we take detailed
spectra, measurements of the energy given off by the object as a function of its
wavelength. An object's spectrum tells much more about an object than its image.
A spectrum can be used to estimate a galaxy's distance and chemical
composition, or to determine a star's age.

Our system can measure many hundreds of spectra simultaneously over a 3 degree wide area,
using a spectral plate. Each plate is an aluminum disc with either 640 or 1000 optical
fibers connected; each fiber points to an object we are observing.
By clicking on
Spectra at the sidebar, you can download
a picture of the spectrum of every object observed spectroscopically. By clicking
on Plate you can browse through a list of all objects from
a given plate, by type and redshift, and look at them individually by
clicking at them.